HISTORIC 



143 



C. 120), who immunized himself against poisons by drinking the blood 

 of ducks that had been treated with the corresponding toxic substances. 



Immunization against various venoms has been practised by many 

 of the savage tribes of Africa since earliest times. Mention has previ- 

 ously been made of the method of preventive inoculation against small- 

 pox practised in Asia and other Oriental countries for several centuries 

 by exposing the subjects to mild cases of the disease. 



A very definite step in progress must ever be associated with the 

 name of Edward Jenner, who first demonstrated experimentally, and 

 in a scientific manner, that cowpox conveyed to man protected him 

 against smallpox. Jenner was not the first person to make this observa- 

 tion, as many of the Gloucestershire farmers knew that cowpox pro- 

 tected them against smallpox; nor was he the first deliberately to in- 

 oculate persons with cowpox virus, as this method had been practised 

 sporadically before his time. Jenner was, however, the first medical 

 man to give the matter serious thought and consideration, and to test the 

 method as thoroughly and scientifically as it was possible to do at that 

 period. Thus he inoculated with smallpox virus those whom he had 

 previously vaccinated with cowpox virus, and found them immune to 

 smallpox. These experiments were courageously repeated, until a great 

 truth was established, which has resulted in almost completely eradi- 

 cating the disease from those countries or communities where vaccina-. 

 tion is thoroughly carried out. As was to be expected, Jenner met with 

 considerable opposition, and this is readily understood when it is re- 

 membered that even today one hundred and eighteen years later 

 there are those who refuse to accept, or are unable to realize, the great 

 benefits of this pioneer work. Jenner could not explain his results; he 

 maintained that he was dealing with a modified form of smallpox. We 

 of today have no better means of establishing the truth of the efficiency 

 of cowpox vaccination, nor have we improved any on his method. The 

 specific germ of smallpox is still undiscovered, and we must agree with 

 Jenner that cowpox is probably a modified form of smallpox and prac- 

 tically harmless, the virus of cowpox being the virus of smallpox 

 modified, attenuated, and rendered practically innocuous by passage 

 through a lower animal. 



Nothing further of importance was accomplished during the follow- 

 ing eighty years, until the next and even greater epoch ushered in the 

 discoveries in bacteriology and the first immunization by Pasteur based 

 on scientific reasoning. The chickens around Paris were being destroyed 

 by a virulent intestinal infection, and Pasteur first isolated the causative 



